This invention relates to computer video controllers.
In personal computers, display of information is typically handled by a dedicated video controller with an associated dedicated video memory. One portion of the dedicated video memory has a frame buffer which corresponds to the pixels to be displayed on a computer monitor. Other portions of video memory can include motion video buffers, buffers for discrete icons (such as cursors, or "pop-ups" displaying system functions like battery life, and the like), and other buffers.
The frame buffer is typically organized in a standard 256K by 16 bit memory architecture, written by a particular width video memory interface. For example, a 32 bit wide video memory interface can access a one megabyte frame buffer, while a 64 bit interface can accommodate a two megabyte frame buffer. The amount of memory required for a given frame buffer, though, is determined by the resolution and dimensions of a given display. For example, a 1024 by 768 pixel display with 16 bits per pixel color depth requires a 1.5 megabyte frame buffer. To accommodate that display, a 2 megabyte dedicated video memory might be required, but this use would "waste" 0.5 megabytes of memory.
Computer manufacturers and users face the choice of paying increased costs to have more dedicated memory to handle higher-resolution displays (and possibly waste extra memory), or accept lower resolution displays. This choice is becoming more important as manufacturers are integrating the video controller and its dedicated video memory all on the same semiconductor die: choice of memory size becomes fixed during manufacture.